SE534155C2 - System and method for controlling a gearbox - Google Patents

Description

534 155 motor torque, from motor 10 to the ECU via, for example, a CAN bus (Controller Area Network).

In conventional gear systems, the control unit 110 uses tabulated engine speed limits, also called gear points, which indicate the engine speed at which a downshift or upshift is to be effected in the gearbox 20, i.e. when the speed of the engine 10 passes an engine speed for a shift point, the motor vehicle 1 shifts. The shift points can therefore be understood as including information partly about when a downshift or upshift is to take place and partly about the number of shift steps to be performed at said downshift or downshift. It is common for each change point to indicate one to three change steps, but more change steps are possible.

Figure 2 shows in principle an example of a number of tabulated shift purity lines forming lines SP 1 -SP6 in a graph where the x-axis represents motor torque and the y-axis the speed of the motor 10 in the unit revolutions per minute (revolutions per minute, rpm). As long as the engine speed is between the l5 gear lines SP1 and SP4, no shift takes place, but if the engine speed goes over a gear line, SP1 -SP3, an upshift is initiated, and correspondingly a downshift is initiated if the engine speed goes below a downshift line, SP4-SP6. The number of upshift and downshift steps for each of the lines SP1-SP6 is given in Table 1 below. For example, if the rotor speed goes over line SP1, an upshift occurs with one shift step and if the motor speed goes below line SPS, a downshift occurs with two shift steps.

SP1 Upshift speed for 1 step up SP2 Upshift speed for 2 steps up SP3 Upshift speed for 3 steps up SP4 Gearshift speed for 1 step down SPS Downshift speed for 2 steps down SP6 Shutdown speed for 3 steps down Table 1: Down and upshift lines shift points SPl-SP6 i.a. driving characteristics, acceleration, comfort and fuel consumption of the motor vehicle 1, so these must be carefully calibrated by the motor vehicle manufacturers. The calibration is carried out in such a way that different shifting strategies are tested in the field during different driving situations, such as at different throttles, road inclines and train weights.

The test results must then be carefully analyzed to determine the appropriate change points.

Automated shifting systems usually include a so-called kickdown function, which means that a downshift is forced if such a function is activated. The purpose is to quickly increase the engine speed on the motor 10 so that a higher power is obtained from the motor 10. However, such a downshift can mean that the engine speed after the downshift turns out to be too high, so a upshift becomes necessary. This means that the number of unwanted changes increases, which is why i.a. riding comfort, fuel consumption, and acceleration are affected.

Figure 3 shows an example of an accelerator pedal 2 in a motor vehicle 1, which accelerator pedal can be rotated about an axis for controlling the accelerator pedal / engine torque, which is illustrated by the dashed arrows in the fi clock. Furthermore, the accelerator pedal comprises a kickdown function, which in this example is initiated if the accelerator pedal 2 is pressed into its bottom position so that a pushbutton or a sensor 3 is activated, the shifting system being given an indication that the kickdown function is to be initiated, for example by an electrical signal sent to a controller ll0.

Brief Description of the Invention An object of the present invention is to provide an alternative sister for controlling a gearbox. Another object of the invention is to provide a system for controlling a gearbox which completely or partially solves the problems of the prior art. A further purpose of the invention is to provide a kickdown function which reduces the number of unwanted shifts.

According to an aspect of the invention, the above-mentioned object is achieved with a system for controlling a gearbox, comprising at least one control unit arranged for controlling said gearbox arranged in a motor vehicle, which motor vehicle comprises a motor connected to said gearbox for driving the same, said system is arranged to receive, when receiving an indication, a gear for shifting said gearbox, said gear belonging to a plurality of possible gears for said gearbox, and said gear causing said engine to obtain a desired engine speed com in a shorter time than with any other gear associated said amount of possible gears. Embodiments of the above system are found in the dependent claims of the above system.

Furthermore, the invention relates to a motor vehicle comprising at least one system as above.

According to another aspect of the invention, the above-mentioned object is achieved with a method for shifting a gearbox arranged in a motor vehicle, which motor vehicle comprises a motor connected to said gearbox for driving the same, said method receiving a gear for shifting upon receipt of an indication. of said gearbox, said gear unit belonging to a plurality of possible gears for said gearbox and said gear unit causing said engine to obtain a desired engine speed com in a shorter time than with any other gear unit belonging to said quantity of possible gears.

The invention further relates to a computer program comprising program code, which when said program code is executed in a computer causes said computer to perform the above method. Furthermore, the invention relates to a computer program product belonging to the said computer program.

The method according to the invention can also be modified according to the different embodiments of the system above.

An advantage of the invention is that when activating the kickdown function, you get access to the maximum power of the engine in the shortest possible time. Another advantage is that unwanted shifts are reduced in connection with the use of the kickdown function.

Additional advantages and applications of a device and system according to the invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed description of the present invention, embodiments of the invention will be described with reference to the accompanying figures, in which: Figure 1 schematically shows a part of a driveline for a motor vehicle; - Figure 2 shows a graph of down and upshift lines; figure 3 schematically shows an accelerator pedal comprising a kickdown function; Figure 15 shows a flow chart of an embodiment of the invention; figure 5 shows a control unit to be part of a system according to the invention.

Detailed Description of the Invention The present invention relates to a system for controlling a gearbox 20 arranged in a motor vehicle 1, such as a truck or bus. Preferably, the gearbox 20 is of the type included in an automated shifting system, which is controlled by a control unit 110, such as an ECU. In such a system, shifts are performed automatically by the control unit 110, but it is also common for the driver to be able to perform manual shifting in such an automated shifting system, so-called manual shift in automatic mode (automatic node). Furthermore, the gearbox 20 has a number of gears, Lex. 12 forward gears and one or fl your reverse gears, something that is common in modern trucks.

To completely or partially obviate the disadvantages of prior art kickdown functions, a system, including a control unit 110, is provided for controlling a gearbox 20 where a gearbox is selected for gearbox 20 from a plurality of possible gears when a kickdown function is initiated. The criterion for selecting gear is that the gear is selected for the gearbox 20 with which the motor 10 reaches a desired engine speed (if, in a shorter time than with any other gear belonging to the set of possible gears.

The set of possible gears is according to an embodiment of the invention: the current gear in which the gearbox operates, or a lower gear. The reason is that you always want to have increased or the same engine speed when activating a kickdown function. For example, assume that a motor vehicle 1 has 12 fi reverse gears and that the motor vehicle is currently running on gear 8. This means that the amount of possible gears in this case is gears 1-8 according to this embodiment, so the number of gear steps can vary between 0-7 downshifts, means that even the 0-gear is an alternative (ie you remain on the same gear).

Regarding the desired engine speed (if, it refers to a desired engine speed for the engine 10).

In this context, it should be understood that the desired engine speed (if, is within an engine speed range, which includes the engine 10 maximum power speed, ie the engine speed when the engine 10 power is greatest. The reason is that by activating a kickdown function you want to get so therefore, the desired engine speed mm, according to an embodiment of the invention, is within an engine speed range defined as the engine 10 maximum power speed +/- Aw, where Aco is an engine speed specified in rpm The order of magnitude of the Aco is preferably 100-300 rpm, however, it is not necessary that the interval defined as maximum power speed +/- Aw is oxygen-centric around the motor 10 maximum power speed, but usually an engine speed of mm is desired, which is just below the maximum power speed 10.

With reference to the fate diagram in Figure 4, at block F 1 it is calculated how long it takes to accelerate to the maximum power speed as without downshift, i.e. i = 0 there indicates the number of downshifts from the current gear when the kickdown function is initiated. Then it is calculated how long it takes to get to the maximum power speed wKD with a downshift step, i = 1, which takes place at block F2. These two times are then compared. If the time to reach the maximum power speed etc. is shorter for i = 0 than for i = 1, the shift system chooses not to perform any shift. Otherwise, the time it takes to reach the maximum power speed (if driving in downshift steps is calculated and compared with the time it takes to get to the maximum power speed (if driving in - 1 downshift step, which takes place at block F3. This procedure is repeated until the downshift step is found). longer time than the previous one, ie il. If this is the case, il downshift steps are performed at block F4.

According to one embodiment of the invention, the time it takes to reach the maximum power speed etc. is calculated using the function: T = TT m power my: + ufcezemnon> where Tmf, is the time it takes for the shift system to change from the current gear to one of the candidates for it. gear that in the shortest time leads to the motor reaching the maximum power speed (if,, ie a gear that belongs to the number of possible gears. This parameter is known by the gear system because it is system-constant. If you calculate the time for a zero gear (ie no gear at all) it is term of course 0. Tacæfenuion is the time it takes to accelerate the motor vehicle 1 to the maximum power speed wKD after shifting. Tawe; e, a ,, - ,,,, which can be derived as follows.

Uti fi- without assuming the relations in equations (1) - (3) below: 10 15 20 25 534 155 7 M = Jø (1), Marre-Qi (2), -2 .1 = m + 1,: _ 2 ( 3), where M is the accelerating moment, J is the inertia of the vehicle, a) is the rotational speed of the engine (engine speed), M, is the moment of the flywheel of the engine, En, is the driving resistance, r is the wheel radius, i is the total gear ratio, m is the mass of the motor vehicle, and I, is the moment of inertia of the engine; whereby the relations are given according to equation (4), HELLO df »M Mfñ *. _: = _ = _? _ 2_ (4), dt J mJrIL ß 2 I 'F “I Me _' än Taccelernlrbn = da)” I m + I _ It is realized that the choice of switch is made in real time by means of the above equations, i.e. each time the kickdown function is initiated. The calculations preferably take place in the control unit when it receives a kickdown indication as described above.

According to another embodiment of the invention, the system also comprises a control means 2 arranged to provide an indication that the kickdown function is to be initiated.

Preferably, the control means 2 is an accelerator pedal 2 comprising a kickdown function. As shown in Figure 3, the accelerator pedal 2 can assume a number of continuous positions between a first end position (corresponding to no throttle) and a second end position (corresponding to full throttle). By depressing the accelerator pedal in its second end position, for example, a push button or a sensor 3 is activated, which leads to the system's kickdown function being initiated. For example, an electrical signal may be sent from the button or sensor 3 to a control unit 110 to be used for controlling the gearbox 20. The invention further relates to a motor vehicle 1, such as a truck or bus, comprising at least one system according to above.

The invention also relates to a method for shifting a gearbox arranged in a motor vehicle l.

The method involves selecting a gear from the set of possible gears when receiving an indication, which means that the motor 10 obtains a desired motor speed wKD in a shorter time than with any other gear belonging to the set of possible gears. The method works essentially according to the fate diagram in Figure 4.

It will also be appreciated that the method and embodiments of the above method may be modified according to the various embodiments of a sister for controlling a gearbox according to the invention.

The person skilled in the art further realizes that a method for changing a gearbox according to the present invention can also be implemented in a computer program, which when executed in a computer causes the computer to perform the method. The computer program is included in a computer-readable medium of a computer program product, said computer-readable medium consisting of a suitable memory, such as for example: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc.

Figure 5 schematically shows a control unit 10 to be part of a system according to the invention.

The control unit 110 comprises a calculation unit 11, which may be constituted by substantially any suitable type of processor or microcomputer, e.g. a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC). The calculation unit 111 is connected to a memory unit 112 arranged in the control unit 110, which provides the calculation unit 111 e.g. the stored program code and / or the stored data calculation unit 111 need to be able to perform calculations. The calculation unit 1 1 1 is also arranged to store partial or final results of calculations in the memory unit 112.

Furthermore, the control unit 110 is provided with devices 113, 114, 115, 116 for receiving and transmitting the input and output signal, respectively. These input and output signals may contain waveforms, pulses, or other attributes, which of the devices 113, 116 for receiving input signals can be detected as information and can be converted into signals, which can be processed by the computing unit 111. These signals are then provided by the computing unit 111. The devices 114, 115 for transmitting output signals are arranged to convert signals obtained from the computing unit 11 for creating output signals. by e.g. modulate the signals, which can be transmitted to other parts of the system for determining down and upshift points. One skilled in the art will appreciate that the above-mentioned computer may be constituted by the computing unit 1111 and that the above-mentioned memory may be constituted by the memory unit 112.

Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may consist of one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Orientated Systems Transport), or any other bus configuration; or by a wireless connection. The connections 70, 80, 90, 100 in Figure 1 may also be one or more of these cables, buses, or wireless connections.

Finally, the present invention is not limited to the above-described embodiments of the invention but relates to and encompasses all embodiments within the scope of the appended independent claims.

Claims (16)

10 15 20 25 30 534 155 10 Patent claims A system for controlling a gearbox (20), comprising at least one control unit (110) arranged for controlling said gearbox (20) arranged in a motor vehicle (1), which motor vehicle (1) comprises a motor (10) connected to said gearbox (20) for driving the same, characterized in that said system is arranged to receive a gear for said gearbox (20) upon receipt of an indication, said gear belonging to a plurality of possible gears for said gearbox (20), and said gear entails that said motor (10) obtains a desired rotor speed wKD in a shorter time than with any other gear belonging to said amount of possible gears. The system of claim 1, further comprising a control means (2) coupled to said system, said control means (2) being arranged to provide said indication. A system according to claim 2, wherein said control means (2) is an accelerator pedal comprising a kickdown function, which gives rise to said indication. A system according to any one of the preceding claims, wherein said desired motor speed etc. is within a motor speed range comprising said motor (10) maximum speed. The system of claim 4, wherein said engine speed range is defined as the maximum power speed of said motor (10) +/- Am, where Aw is an engine speed value in rpm and is of the order of 100-300 rpm. A system according to any one of the preceding claims, wherein said gear is the current gear or a lower gear, A system according to any one of the preceding claims, wherein said switch is selected on the basis of real-time calculations. 10 15 20 25 534 155 ll A system according to any one of the preceding claims, wherein said gear minimizes the time function: TW m ”= Išhm + Tamkwn, where TW, is the time for performing a shift and Tácukmm is the time it takes to accelerate said motor vehicle (l) to the maximum power speed after exchange; among all the gears belonging to said quantity of possible gears. The system of claim 8, wherein Támmm is determined by: F Mc __ 788 ,. Tmekmm = da), where M e is a moment for said flywheel of said motor (10); I, z is M m + IerT said motor (10) moment of inertia; and wherein Fm, r, in respective m is a driving efficiency, a wheel radius, a total gear ratio and a mass, respectively, of said motor vehicle (1). A system according to any one of the preceding claims, wherein said indication is an electrical control signal. A system according to any one of the preceding claims, wherein said gearbox (20) is an automatic gearbox or an automated manual gearbox comprising a number of gears, and said motor vehicle (1) is slightly belonging to the group: truck and bus. A system according to any one of the preceding claims, wherein said amount of possible gears is the current gear and other lower gears for said gearbox (20). A motor vehicle (1), such as a truck or bus, comprising at least one system according to any one of claims 1-12. A method of shifting a gearbox (20) arranged in a motor vehicle (1), which motor vehicle comprises a motor (10) connected to said gearbox (20) for driving the same, said method being characterized in that upon receiving a indication selecting a gear for said gearbox (20), said gear belonging to a plurality of possible gears for said gearbox (20) and said gear means that said motor (10) obtains a desired motor speed etc., in a shorter time than with any another gear belonging to said quantity of possible gears. A computer program comprising program code, which when said program code is executed in a computer causes said computer to perform the method of claim 13. A computer program product comprising a computer readable medium and a computer program according to claim 14, wherein said computer program is included in said computer readable medium belonging to any of the group comprising: ROM (Read-Only Memory), PROM (Programmable ROM), EPROM (Erasable PROM), F lash memory, EEPROM (Electrically EPROM) and hard disk drive.